The best punishment for all rapist is death penalty so it will less the criminals to do the violence act because they will now scared and fear to do that,they will think it twice if they can doing that or not because they will think that their life might be in danger because of death penalty
There are a lot of people in the world, who are not afraid of death. So death penalty is not the ultimate solution. IMO, there is a better method. Rapists must be castrated in the public, and then they should be sent to some labor colony to spend the rest of their lives. Any compensation from their wages must be directly given to the victim.